@Gigamaxx,
When it comes to heavy duty compute performance the Radeon VII will always beat the RX 5700 XT hands down due to its higher number of compute units (60 vs 40 on 5700 XT), in addition it has 16GB of HBM2 memory that has a 4096 bit memory interface giving it a max bandwidth of 1024 GB per second resulting in a Peak Single Precision Compute Performance of 13.8 TFLOPs.
RX 5700 XT uses 8GB of GDDR6 memory with a 256 Bit memory interface giving it a max bandwidth of 448 BG per second. It makes up some ground against the Radeon VII due to the efficiency of its new RDNA architecture coming in at a Peak Single Precision Compute Performance of 9.75 TFLOPs.
The numbers speak for themselves ... Radeon VII is around 41% more powerful than 5700 XT in Peak Single Precision Compute Performance.
Of course it depends on the task at hand and how well optimised the application being used is, but as long as the host system is able to push the data to the Radeon VII fast enough it will leave a 5700 XT in it's tracks. it's a beast of a GPU when it comes to raw compute performance.
Not saying that the 5700 XT is a poor card quite the opposite in fact, for it's price it punches well above anything else at that price point but if your looking for sheer compute performance on MacOS then the Radeon VII is still king (for the moment).
Once Apple get the 5700 series drivers stable and optimised I think a 5700 will become the new goto GPU for 95% of hackintosh systems .. only heavy duty 4K/8K video editing or very complex 3D work will need anything more powerful.
I'm not taking into account gaming performance as that something i personally don't do so can't really comment on it.
As you say it will be very interesting to see what AMD has been up to when it releases Navi21 & Navi23 next year, they could be absolute beasts ... I suspect that we'll see the them released first as an add in card for the new Mac pro giving it even more compute power (at a even higher cost) ...
Cheers
Jay